This invention relates to a synchronous buffer circuit and a data transmission circuit using the synchronous buffer circuit. More particularly, this invention is concerned with a synchronous bidirectional buffer circuit used to transfer data from or to a transmission line terminated by terminating resistors, and a data transmission circuit including the synchronous bidirectional buffer circuits.
In general, a low-amplitude level is often used as a fashion for transmitting data at a high speed over a transmission line. Since the adoption of a low amplitude enables minimization of reflection of a signal, fast transmission can be achieved. It is known that a conventional data transmission circuit is known as an exemplary data transmission circuit using a low-amplitude level.
Reflection of data occurs at terminals of a transmission line in the conventional data transmission circuit, as will be described later. It is therefore essential to absorb the reflection fully.
However, it is in practice very difficult to fully absorb reflection in the conventional data transmission circuit.
In order to reduce the reflection, a time instant at which an output level changes from a low level to a high level has been delayed on purpose in an effort to minimize reflection. An output waveform may be trimmed with respect to a slew rate in order to absorb a reflected wave. This method cannot help inviting a decrease in a data transmission rate.